I'm a big believer in model railways learning not just from other modelling disciplines but also from the world of theatre and the arts. There is, of course, a long tradition of this.
I've just come across these 3d cardboard forests by Eva Jospin
It strikes me that 4mm versions of these would work really well as a backdrop for a layout, and that they could even be moulded.
Layout Design Blodwell Buildings The Art of Compromise Photography Llanrhaiadr Mochnant Scenery Signal Box Baseboards Goods Yard Track 45XX Apa Box EM Lcut Creative Travel Backscene Concepts Railway Exhibitions TVR USA Upwold 14XX Anyrail Bridge Cuba Cycling Fencing Lorry Narrow Gauge Point rodding Points Templot Turnouts West Maryland Books C+L Fiddleyard GWR Hales OO9 Phil Parker Rolling Stock Signals State of the hobby Tillig Warley Weighbridge trams 2012 AC Railbus Albion Yard Allt-y-Graban Rd Apa Valley Balloch Pier Bas Bath Green Park Brickwork Bridgnorth Bryn-y-Felin CSX Charmouth Clarendon Class 25 Cliff Railway Coldrennick Road Corris Crich DCC Disused Railways Dukedog EMGS Edwin Smith Electrics Emett France Gloucestershire & Warwickshire HO Hobbies Hope under Dinmore Hospital Gates Iain Rice Iliffe Stokes Inspiration Ireland Kings Lynn La Baraque Lasercut Leamington & Warwick Locos MSTS Mainly Trains Military Modeling Mishaps N guage NEC OOn3 Percy Pier Railway Porth y Waen Preserved Railways RTR SMP Seend Sentinel Sketchup St Minions Stockholm TGV TRAX Tansey Bank Techniques Technology Tim Horn Trade Trees Ultrascale Veldhoveh 1935 Watertank Williamsport diorama manning wardle painting procrastination pug ships simulators